Carpets are generally produced by tufting carpet yarns into and through a primary backing which is comprised of a woven or non-woven material or a combination of such materials. The tufting process will generally produce an intermediate product comprised of loops of yarn which protrude through a “face” side of the primary backing and are retained by a plurality of “back stitches” on the back side of the primary backing. The carpet loops which protrude through the primary backing may then trimmed to leave cut pile yarns on the carpet face, or they may be left as loop pile. In either event, the back stitches on the back side of the primary backing are generally covered with a back coating adhesive material to provide “fiber lock” so that the fibers of the tufts are retained together, and “tuft bind” so that the tufts cannot be easily pulled through the backing. It is common for the back coating material to be applied in liquid form by direct coating, and frequently, a secondary backing of jute or other woven material such as ActionBac® woven polypropylene backing is then applied over the back coating material. The primary and secondary backings are typically pressed together between a pair of lamination press rolls, and the greige good, the intermediate product comprising the primary backing with yarn tufted therethrough, the back coating material and the secondary backing, is then heated or subjected to a chemical or other treatment to cure or fix the back coating in a solid state, thereby binding the primary backing and the secondary backing together by means of the back coating material. In some cases, no secondary backing is applied, and the back coating is solidified after application to the primary backing. In other cases, the back coating is solidified after application to the primary backing, and a secondary backing is applied to the solidified back coating on the primary backing using a separate adhesive material.
Styrene butadiene rubber (“SBR”) latex with various fillers is commonly used as a back coating material. This material is cured by heating which causes the evolution of water vapor from the SBR latex, thereby changing it from a liquid form into a solid. Since SBR latex generally maintains its viscosity and tackiness during processing, the greige good is usually conveyed through a curing oven with the “face” side up. Other natural and synthetic latex materials, including ethylene vinyl acetate and acrylic, may also be used in a similar manner.
Non-latex adhesive materials have also been used as back coatings or adhesives for secondary backings. Such materials include polyurethanes, hot melt adhesives of various compositions, polyvinylchloride and meltable powders. Such coatings may be applied to greige goods by use of conventional carpet coaters; however, greige goods with such coatings are generally conveyed face down through a curing oven. Polyurethane coatings were introduced during the early 1970's by Union Carbide Corporation. (see Journal of Cellular Plastics, Vol. II, No. 6, Nov/Dec, 1975). Shortly thereafter, Dow Chemical also produced and marketed a polyurethane coating. (see Review Crosstalk, Vol. 43, No 3, June 1993). The use of polyurethane coatings requires expensive handling equipment for application to the primary backing or back coating on the primary backing. Polyurethane coatings are principally used as unitary coatings on synthetic grass products and on carpet precoated with urethane foams for residential and commercial use. However, U.S. Pat. No. 6,299,715 of Langsdorf et al. describes the application of a reactive urethane back coating and the lamination of a secondary backing to the primary backing using press rolls much like in the conventional latex coating operation. Because polyurethane coatings are generally less viscous than latex coatings (and consequently susceptible to dripping), the coating is applied to the carpet, and the carpet is conveyed through the curing oven in a face down orientation. U.S. Pat. No. 6,264,775 of Holeschovsky et al. describes a use of a urethane adhesive which includes non-Newtonian thickeners that reduce the likelihood of dripping, thereby permitting the processing of carpet by passing it through a curing oven in a face-up orientation, as in most latex operations.
U.S. Pat. No. 4,171,395 of Tillotson describes a process for forming a layer of foam urethane on a carpet backing by applying a release film or layer of latex on a Teflon®-coated conveyor belt, curing the latex on the belt using a hot air dryer, pouring a urethane foam reaction mixture onto the cured latex film and shaping it into a layer of specified thickness. The primary backing of a tufted carpet is laid onto the layer of reaction mixture on the release film, and the reaction mixture is then heated to chemically blow foam therefrom by the generation of carbon dioxide in the reaction process. U.S. Pat. No. 4,405,393, also of Tillotson describes a similar process in which an elastomeric film, which may consist of “a layer of an olefin material such as polyethylene or polypropylene, or a layer of polyvinyl chloride or rubber lattices such as natural or synthetic SBR latex rubber”, is substituted for the latex release film.
Thermoplastic powders such as polyethylene powders are also used as back coating and adhesive materials. Such powders have been used for some time for automobile carpets; however, they have only recently been used in connection with broadloom carpets. In the late 1990s, Sellers Engineers, Ltd. developed a powder coating for use in applying a woven secondary backing to a primary backing. According to this process, a latex adhesive was applied without any filler to the primary backing. The latex was cured and a polyethylene powder was applied. The powder was heated using infrared heaters to melt it, and then a jute or woven fabric secondary backing was applied and laminated to the primary backing using cold press rolls.
Although latex and thermoplastic powder back coatings and adhesives may provide acceptable fiber lock for a primary backing and acceptable lamination adhesion for a secondary backing, such back coatings are generally porous and do not prevent fluid spills from penetrating from the surface of the carpet through to the carpet pad or cushion and/or to the floor beneath. Such spills may create odors that cannot be removed and provide a haven for bacteria. Therefore, it is frequently desirable to provide a carpet having a fluid barrier that can retain a spill above the carpet pad or flooring (or within the carpet) where it may be easily removed. An effective fluid barrier may be obtained using polyurethane, providing that very high coating weights of at least about 50 ounces per square yard are employed. However, as mentioned above, polyurethanes are expensive and require special handling and processing equipment. Another fluid barrier that may be used is the SPILLNET™ protective barrier that is made and sold by DuPont. However, the SPILLNET™ barrier is not a part of the carpet product but instead comprises a separate plastic sheet that is installed on top of the carpet pad or cushion before installation of the carpet. This increases the cost of the carpet installation, as well as the labor required.
My U.S. Pat. No. 5,612,113 describes a carpet with a fluid barrier comprised of an impervious film that is bonded to the back of the primary backing or to the back of a secondary backing after curing of the latex back coating using a non-aqueous adhesive such as a hot-melt thermoplastic adhesive or a polyurethane. The application of this fluid barrier thus requires a processing step after the normal latex curing step, whether the fluid barrier film is applied over the primary backing or over a secondary backing. My U.S. Pat. No. 5,962,101, No. 6,475,592 and No. 6,479,125 describe multi-layer primary backings which may include a plastic sheet material; however, the plastic sheet material of these primary backings may not provide a fully-effective fluid barrier because it is pierced by the carpet yarns that are tufted through it.
In the production of synthetic grass carpets for athletic and landscape use, it is common to employ a primary backing that is porous or permeable to liquids. Sometimes, a primary backing is mechanically perforated to improve its porosity. Occasionally, a secondary backing is applied to the back side of the primary backing and both backings are perforated simultaneously to allow for the drainage of rain water and other liquids through the carpet.
U.S. Pat. No. 4,705,706 of Avery describes an artificial turf product made of polyethylene yarn and a woven nylon primary backing. The polyethylene yarn is tufted through the woven backing and heat is applied to the back stitches to bond them to the nylon primary backing. The backing may comprise multiple layers in order to allow for infiltration and retention of sand in the carpet; however, no secondary backing is used. The woven primary backing of this outdoor turf product allows water to filter through the sand and the primary backing.
U.S. Pat. No. 5,958,527 of Prévost describes a synthetic grass carpet comprising a plurality of synthetic ribbons that are tufted through a two-ply open weave fabric primary backing. Three infill layers are added, comprising a base course of sand, a middle course of intermixed sand granules and rubber granules, and a top course of rubber granules. U.S. Pat. No. 6,338,885, also of Prévost, describes a similar synthetic grass carpet in which polyethylene or polypropylene ribbons are tufted through a primary backing comprising two layers of woven or needle punched polypropylene fabric. In one embodiment of the carpet product of U.S. Pat. No. 6,338,885, at least a portion of the back side of the primary backing is coated, using a porous back coating material to secure the back stitches to the primary backing. U.S. Pat. No. 6,551,689, also of Prévost, describes a similar synthetic grass carpet in which polypropylene, polyethylene, nylon or plastic ribbons are tufted through a primary backing comprising two or more layers of open weave fabric, one of which may be a dimensionally stable netting. None of the carpets described in the Prévost patents referenced above includes a secondary backing.
It would be desirable if a carpet could be developed which includes a secondary backing comprising a fluid barrier film, a fabric or a laminate that may be applied without the use of a separate adhesive. It would also be desirable if a method or process for manufacturing a carpet with a secondary backing comprising a fluid barrier film, a fabric or a laminate could be developed which would require less expensive equipment and could be carried out at a lower capital cost than known processes. It would also be desirable if a method or process for manufacturing a carpet with a such a secondary backing could be developed which would require less energy and could be carried out at a lower operating cost than known processes. It would be desirable if such process would permit recycling of such carpet by conventional means.